1. Field of the Invention
The present invention relates to an improved method of manufacturing emulsions of a water immiscible phase in an aqueous phase. Emulsions of this type are widely employed in the cosmetic and toiletry industries.
2. Description of the Prior Art
Cosmetic and toiletry creams and lotions are widely manufactured as emulsions of a water immiscible phase in an aqueous phase. In order to finally disperse particles of the water immiscible phase in the aqueous phase, substantial amounts of an emulsifier are employed according to conventional manufacturing techniques. Suitable emulsifiers are rather expensive and represent a considerable portion of the cost of the emulsion product. Also, emulsifiers do represent a skin irritant in the emulsion product.
Furthermore, with conventional manufacturing techniques which rely upon emulsifiers to disperse an oil phase within an aqueous phase, emulsification is usually carried out at an elevated temperature of perhaps 70 to 80 degrees Celsius. Many of the components of cosmetic and toiletry emulsions, such as perfume oils, are sensitive to temperature. Such temperature sensitive materials exhibit a loss of activity when subjected to the relatively high temperatures employed in conventional emulsification manufacturing techniques. As a consequence, relatively large quantities of these heat sensitive materials are required in the products to compensate for the loss of activity caused by subjecting them to elevated temperatures.
A further disadvantage of conventional emulsification techniques is that, due to the relatively high temperatures employed, a considerable time is required for the emulsified product to be cooled. This increases the labor cost for each batch of materials and reduces the throughput period. That is, the cooling time represents a limiting factor on the number of batches of product which can be produced with available equipment.
As used herein, an emulsifier is considered to be a substance which lowers surface tension only for the purpose of promoting emulsification, as contrasted with the broader term surfactant which applies to substances which lower surface tension for other purposes as well. For example, methyl paraben is a surfactant but is not an emulsifier.